[SR-Users] Create accounta with multiple DIDs

I am novice in the area and i have a Kamailio basic setup where i create users and each user can call each other. No connection to an ITSP. i am trying to simulate things and need to send multiple numbers to each user. For example i have users 1000-1003. I need each user to have a range of 100 numbers (fake since it ia not connected anywhere) and routed to all the other users as well. The idea is to connect Asterisk servers and each one have a registered account 1000-1003. Then each Asterisk's extension have a particular DID and call another Asterisk server to a different DID. Off course this will go through Kamailio. Now i call from one Asterisk to the other by using the 1000-1003 and it works. But i need the DID routing